WDPN32 PGTW 222100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 05W (GAEMI) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.4N 124.8E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 316 NM NORTHEAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 24 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTION FIGHTING MODERATE (15-20KT) VERTICAL WIND SHEAR FROM THE
NORTH, PARTIALLY EXPOSING THE WESTERN PORTION OF THE LOW-LEVEL
CIRCULATION CENTER (LLCC) BRIEFLY AS THE SYSTEM HAS REMAINED
QUASI-STATIONARY (QS) OVER THE LAST 6 HOURS. THE WEAK TRACK MOTION
CAN BE ATTRIBUTED TO A WEAK STEERING ENVIRONMENT BETWEEN A
DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTHWEST AND A DEEP-LAYER
SUBTROPICAL RIDGE TO THE EAST. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE EVIDENT PARTIAL LLCC BRIEFLY DEPICTED
IN ANIMATED EIR. THE INITIAL INTENSITY IS PLACED WITH LOW CONFIDENCE
BASED ON AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: WEAK STEERING BETWEEN A SUBTROPICAL
RIDGE TO THE NORTHWEST AND A SUBTROPICAL RIDGE TO THE EAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 59 KTS AT 1800Z
   CIMSS ADT: 63 KTS AT 1900Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 31-32 CELSIUS
   OUTFLOW: STRONG EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON (TY) 05W GAEMI IS FORECAST TO TRACK
NORTH-NORTHWESTWARD OVER THE NEXT 24 HOURS AS THE SUBTROPICAL RIDGE
TO EAST BUILDS IN A WESTERLY DIRECTION. FOLLOWING, THE SYSTEM WILL
CURVE NORTHWESTWARD THROUGH TAU 72 UNDER INFLUENCE OF THE SAME
SUBTROPICAL RIDGE. BEYOND TAU 72, LAND INTERACTION WILL CAUSE THE
SYSTEM TO COME UNDER THE INFLUENCE OF THE CLIMATOLOGICAL
SOUTHWESTERLY FLOW AND TRACK TO THE NORTHEAST. TY 05W (GAEMI) IS
FORECAST TO INTENSIFY GRADUALLY OVER THE FIRST 24 HOURS WHILE IN AN
ENVIRONMENT WITH FAVORABLE UPPER-LEVEL DIVERGENCE, SEA SURFACE
TEMPERATURES BETWEEN 31-32C, HOWEVER THE MODERATE VERTICAL WIND
SHEAR THAT WILL REMAIN BETWEEN 15-20KTS OVER THE NEXT 12HOURS,
MITIGATING THE RATE OF INTENSIFICATION. FROM TAU 12-24, VERTICAL
WIND SHEAR WILL DECREASE SIGNIFICANTLY AND THE SYSTEM WILL
INTENSIFY FOR A BRIEF TIME PERIOD REACHING A PEAK OF 95KTS BY TAU
36 BEFORE BECOMING SHEARED AS THE TYPHOON INTERACTS WITH MAINLAND
TAIWAN BETWEEN TAU 36-60. TC 05W IS FORECAST TO MAKE LANDFALL ON
MAINLAND CHINA BY TAU 72, AT WHICH TIME THE SYSTEM IS EXPECTED TO
WEAKEN DUE TO LAND INTERACTION UNTIL FULLY DISSIPATING BY TAU 120. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE SYSTEM WILL TRACK NORTHWESTWARD THROUGH TAU 72 BUT BEGINS
TO VARY IN TRACK AS THE SYSTEM BEGINS TO INTERACT WITH LAND.
NAVGEM, GFS, AND UKMET TAKE THE SYSTEM TO THE SOUTHWEST AFTER
LANDFALL, BUT THE JTWC FORECAST ALIGNS MORE CLOSELY TO GALWEM,
GEFS, EC-EPS, AND JGSM WHICH TAKE THE SYSTEM NORTHEASTWARD. THE
JTWC INTENSITY GUIDANCE IS IN GOOD AGREEMENT THAT THE SYSTEM WILL
PEAK AROUND TAU 36 BUT VARIES IN HOW STRONGLY THE SYSTEM WILL
INTENSIFY. RAPID INTENSIFICATION AIDS RIPA, RICN, AND FRIA WERE
TRIPPED, HOWEVER IT APPEARS THAT THE JTWC CONSENSUS GUIDANCE IS
INDICATING MORE VERTICAL WIND SHEAR THAN PREVIOUSLY INDICATED.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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